/Engine/Plugins/Online/OnlineServices/Source/OnlineServicesCommon/Public/Online/SessionsCommon.h
[TOnlineResult](API\Plugins\OnlineServicesInterface\Online\TOnlineResult)< [FGetMutableSessionById](API\Plugins\OnlineServicesCommon\Online\FGetMutableSessionById) > GetMutableSessionById ( [FGetMutableSessionById::Params](API\Plugins\OnlineServicesCommon\Online\FGetMutableSessionById\Params) && Params ) const